In computer technology it is well known to build up a network of connected devices for exchanging data and sharing hardware resources. The separate devices are commonly called nodes. At the time being, nodes are usually computers, but can be other technical devices, and their interconnections are mainly electrically, optically or wireless radio connections. Networks can be classified as being based on either client-server or peer-to-peer (P2P) architectures. In P2P based networks a node is also referred to as a peer. While in client-server architectures each node is defined to be either client or server, there is no such differentiation in P2P networks. Instead, peers include both, server and client functionalities. P2P technology enables each node to be capable of providing services or resources to any other node in the network, or use services or resources provided by any other node in the network.
P2P networks are usually not restricted to any special applications or underlying network topologies, but can be understood as a set of nodes, or peers, which rely on certain sets of specific protocols. It is characteristic for a P2P network that the peers communicate directly with other peers, so that no central network organization is required. Most P2P networks support that peers can be connected to the network or disconnected from the network at any time.
The mentioned P2P protocols are required for basic network organization, such as e.g. discovery of other connected peers, offering own services or resources to other peers (advertising), understanding other peers' advertising messages, or allocating connection capacity for establishing certain connections to other peers. Also, there are protocols that enable a group of peers to cooperate, and thus form a peer-group. Such peer-groups are usually used for providing a common set of services within the peer group. Nevertheless, the purpose of a peer-group is not generally defined. A peer belonging to a peer-group normally has access to, and can be accessed from, all other connected peers of the same group. Additionally, each peer may be a member of further peer-groups. For adding or removing peers to or from a peer group, the user is always required to perform certain administrative activities.
Generally only authorized users have access to the peers, or to the peers' contents, or to released parts of the peers' contents, where authorization of the user is achieved by a user-specific key, either physical or virtual secret key, e.g. password.
Since peers must be regarded as individuals, it is necessary that each peer can be unambiguously addressed by using an identifier. Usually a peer is addressed by using a unique label, e.g. a so called Universal Unique Identifier (UUID).
When peers form a peer-group, the peer-group as such usually gets a dedicated label, e.g. UUID, which can be used for identifying the members of the group.
The described peer-to-peer networks and mechanisms are in a detailed manner published e.g. in WO 02/057917 A2.